Why can homonuclear molecules be gasses at STP, but be liquids when they are combined?

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For example, H2O.

In: Chemistry

2 Answers

Anonymous 0 Comments

The behavior of a bulk material depends heavily on how its molecules interact with each other. How molecules interact depends a lot on the positioning of bonds and types of bonds within those molecules. In homonuclear molecules, the bonds tend to be symmetrical and thus no dipole forms. Dipole is where one atom becomes more negatively or positively charged than the other, and this causes the whole molecule to behave like an electret (like a magnet but for electrostatics instead of magnetism). These magnet-like molecules are much more sticky to one-another than non magnet-like molecules of similar size.

Anonymous 0 Comments

Because that’s the way chemistry works.

I assume the reason you’re asking this is that you have an intuition that when you combine two similar objects the combination is also similar. While this is often true, it’s not true for chemistry. Chemistry is full of examples of combining two objects and getting one with wildly different properties. That’s just how chemistry works.